1. Field of the Invention
The present invention relates to an electronic apparatus, and particularly to an electronic apparatus for data input/output processing to a predetermined input/output device.
2. Description of the Prior Art
Generally known electronic apparatuses such as personal computers, word processors and the like include electronic apparatuses which receive data from and transmit data to external printers and other electronic apparatuses. Such electronic apparatuses having the input/output function include various types of apparatuses such as desk-top computers, lap-top computers, hand held computers and the like. Lap-top computers and hand held types of apparatuses are frequently driven by a battery or supplied with electricity using DC electric power, such as an AC adapter, externally attached or the like, because importance is attached to portability.
It is known that the above-described electronic apparatus have a printer interface or a communication interface such as RS232C, or the like, which is provided on the outside thereof, not in the apparatus body, in order to decrease the size and weight of the body or decrease the cost.
In such a configuration, the interface is frequently supplied with electricity from the body side, like the case in which an interface is contained in the apparatus. This is designed for decreasing the size and weight of a communication interface of the like or decreasing the cost.
As is generally known, a central processing unit, CPU and a memory which constitute a control section of the electronic apparatus cannot be normally operated until a stable supply voltage of at least a predetermined value is supplied thereto. However, the above-described conventional apparatus can become inoperative during communication due to a combination of a drop in the supply voltage caused by the operation of the body and a voltage drop caused by the operation of the communication interface externally attached to the body. In this case, there is also the danger of destroying important user data stored in the memory.
An interface such as RS232C, a centronics port, or the like generally conducts a relatively large driving current and thus there is a higher probability that the above problems will be produced than that in the case where the body only is driven.
Although the case where a communication interface is externally attached is described above, the case where the interface is contained in the apparatus body also has the same problem that the apparatus becomes inoperative during communication.